Quick Answer: On a £50,000 salary, sacrificing £5,000 into your pension reduces your take-home pay by £3,600.00. You save £1,000 of Income Tax and £400 of National Insurance, so £5,000 lands in your pension for a net cost of £3,600 -- effective relief of 28%. The same £5,000 through a personal pension would cost £4,000, because that route saves no National Insurance.
Overview
Salary sacrifice works by reducing your gross pay in exchange for an employer pension contribution. Because the money never counts as your salary, it escapes both Income Tax and National Insurance.
That second saving is the entire point. A personal pension contribution gets Income Tax relief but no NI relief, so it costs more for the same amount in your pension. On a basic rate salary the gap is 8 percentage points; the arrangement is worth more the higher your marginal rate.
It also cuts your employer's NI bill by 15% of the sacrificed amount. Some employers add that saving to your pension, which materially improves the deal. Many keep it.
How This Is Calculated
Step 1 -- Reduce the gross salary. The sacrificed amount is subtracted from gross pay before anything else happens.
Step 2 -- Recompute Income Tax and National Insurance on the reduced salary, using the bands for your region. Both fall.
Step 3 -- The cost to you is the difference between your take-home pay before and after:
Step 4 -- Compare with a personal pension. A personal contribution of the same gross amount saves Income Tax but not National Insurance, so its net cost is the contribution less the Income Tax saved. The difference between the two routes is exactly the NI saved.
Step 5 -- Employer NI. Sacrifice reduces the employer's secondary Class 1 liability at 15% on the amount given up. If they pass it on, it is added to the pension.
Worked Example
£50,000 salary, £5,000 sacrificed:
- Take-home before: £39,519.60. Take-home after: £35,919.60
- Cost to you: £3,600
- Income Tax saved: £1,000 (20% of £5,000). NI saved: £400 (8% of £5,000)
- £5,000 into the pension for £3,600 is 28% effective relief
- Via a personal pension the cost would be £4,000, so sacrifice is £400 better
- Employer saves £750 of NI (15% of £5,000)
£70,000 salary, £10,000 sacrificed:
- Higher rate taxpayer: 40% Income Tax plus 2% NI above the Upper Earnings Limit
- Cost to you: £5,800 for £10,000 in the pension -- 42% effective relief
£120,000 salary, £20,000 sacrificed:
- This income sits in the £100,000 to £125,140 band where the Personal Allowance is withdrawn
- Sacrificing restores the allowance, so relief is the 60% effective rate plus 2% NI
- Cost to you: £7,600 for £20,000 in the pension -- 62% effective relief, the best available anywhere in the UK tax system
What This Does Not Account For
- The £60,000 annual allowance, and its taper for high earners, which caps how much can go into a pension with relief in a year.
- The National Minimum Wage floor. Sacrifice cannot reduce pay below the minimum wage, which limits it for lower earners.
- Effects on other pay-linked figures. Reduced gross pay can lower mortgage borrowing capacity, death-in-service cover, redundancy pay and maternity pay, all of which are usually calculated on salary.
- State benefit entitlements. Sacrificing below the Lower Earnings Limit can affect National Insurance credits toward the State Pension.
- Whether your employer offers it. Salary sacrifice requires a contractual variation and an employer willing to operate it.
- Non-pension sacrifice, such as electric cars, cycle to work, or childcare vouchers, which have their own rules.
- Scottish intermediate and advanced rates, which are applied by the engine but produce marginal rates that differ from the rUK examples above.
- Announced changes. Sacrifice has been reviewed repeatedly by successive governments, and its NI advantage is not guaranteed indefinitely.
Common Pitfalls
- Comparing sacrifice with a personal pension on tax alone. The Income Tax relief is identical. The whole advantage is the National Insurance, which is why the two routes cost different amounts for the same pension contribution.
- Assuming the employer's NI saving reaches your pension. They save 15% of whatever you sacrifice, but they are not obliged to pass it on, and many do not. It is worth asking.
- Forgetting it reduces your stated salary. Mortgage lenders assess post-sacrifice pay. Sacrificing heavily just before a mortgage application can reduce what you can borrow.
- Missing the 60% band opportunity. Between £100,000 and £125,140 the effective relief is 62%. If you are in that band and not sacrificing, this is usually the single most valuable thing available to you.
- Sacrificing below the minimum wage. Not permitted, and the arrangement will be unwound.
- Ignoring the annual allowance. Contributions above £60,000, or a lower tapered figure for high earners, attract a charge that can undo the benefit.
Frequently Asked Questions
How is salary sacrifice better than just paying into a pension?
What is the effective relief rate?
Does my employer have to pass on their NI saving?
Will it affect my mortgage application?
Is there a limit?
Does it work the same in Scotland?
Sources
- GOV.UK: "Income Tax rates and Personal Allowances" and gov.scot for the Scottish bands
- GOV.UK: "National Insurance rates and categories" -- Class 1 employee rates of 8% and 2%
- GOV.UK guidance: "Rates and thresholds for employers 2026 to 2027" -- employer secondary rate of 15% above the £5,000 Secondary Threshold
- GOV.UK: "Salary sacrifice for employers" -- the contractual basis and the National Minimum Wage restriction
- All figures verified on 30 August 2026 and mirrored in engine/tables/2026/uk-2026-27.json